The Effect of Orally Supplemented Melatonin on Larval Performance and Skeletal Deformities in Farmed Gilthead Seabream (Sparus aurata).

Kamel Mhalhel,Giuseppe Montalbano,Rosaria Laurà,Maria Cristina Guerrera,Francesco Abbate,Antonino Germanà,Maria Levanti

doi:10.3390/ijms21249597

Kamel Mhalhel, Giuseppe Montalbano + Show 5 more

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https://doi.org/10.3390/ijms21249597

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Abstract

The gilthead seabream larval rearing in continuous light is common in most Mediterranean hatcheries to stimulate larval length growth and increase food consumption. Several studies have shown that continuous light affects larval development and increases the prevalence of skeletal deformities. Melatonin is a crucial pineal neurohormone that displays daily secretion patterns, stimulates cell proliferation and embryonic development in Atlantic salmon and zebrafish, and improves osseointegration in mice and humans. However, no studies have examined the effects of orally supplemented melatonin on skeletal deformities in Sparus aurata larvae. We administered exogenous melatonin to gilthead seabream larvae via enriched rotifers and nauplii of Artemia. Exogenous melatonin induced bone deformities and stimulated parathyroid hormone-related protein-coding gene (PTHrP) mRNA expression. In addition to the melatonin-induced PTHrP high expression level, the recorded non coordinated function of skeletal muscle and bone during growth can be the fountainhead of bone deformities. Both myosin light chain 2 (mlc2) and bone gamma-carboxyglutamate protein-coding gene (bglap) expression levels were significantly affected by melatonin administration in an inverse dose–response manner during the exogenous melatonin administration. This is the first study to report the effect of inducing melatonin bone deformities on Sparus aurata larvae reared under ordinary hatchery conditions.

Highlights

The presence of morphological abnormalities in farmed gilthead seabream (Sparus aurata) is a major problem for current aquaculture as it entails significant economic losses [1,2,3]
At 23 days post hatching (DPH), the highest length was recorded in the control group (Ctrl) group (0.614 ± 0.0155 cm) which was statistically different only from MEL1 (Mann–Whitney U test, p < 0.05) (Figure 1)
The promising values recorded on the Ctrl group, compared to the result already published for this species [9,30,33,35], indicated that the rearing conditions applied in the hatchery were optimal compared to those employed in the above-mentioned studies

Summary

Introduction

The presence of morphological abnormalities in farmed gilthead seabream (Sparus aurata) is a major problem for current aquaculture as it entails significant economic losses [1,2,3]. Several other studies have shown that continuous light affects larval development and increases the prevalence of skeletal deformities [12]. Melatonin production begins immediately after hatching to reach maximum levels between the 6th and 10th day after hatching [23] At this time, levels of hormones involved in growth, metabolism and development, i.e., growth hormone and prolactin, are very low [24,25]. In light of all these bibliographic data, we thought that the inhibition of melatonin by continuous light, especially during the first days after hatching, increases the prevalence of skeletal deformities (especially operculum deformities) and alter larvae growth and development. In the present study we evaluated the effect of an exogenous melatonin supplementation on skeletal deformities (especially the opercular complex abnormalities) and larval performance of gilthead seabream

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